The present invention is directed to a magnetic coil with an essentially hollow-cylindrical coil body or bobbin composed of an insulating material that is provided with two terminal pins anchored in an end region of the coil bobbin, which bobbin has a cylindrical core forming a winding space comprising two different radii adjoining one another in an axial direction.
German 29 514 315 U1 discloses a magnetic coil bobbin having cylindrical cores of two different diameters adjoining one another in an axial direction. However, this does not propose the step-shaped transition between the winding cores, but only an oblique transition with a slope of around 30.degree.. The coil therein, moreover, is provided for winding upon the lower to the higher level, since the winding wire would otherwise slip off.
These coils are especially suited for utilization in the automotive field, for example, as valve coils for ABS systems, whereby a lacquered winding wire that resists various stresses is often employed for such applications, which include being electrically and mechanically connected to the coil-side end regions of the terminal elements. It is standard to hermetically encapsulate the finished winding by a plastic extrusion coating technique.
There is a desire, in some applications, to fashion the coil body with cores, which form the core of the winding space, with, in particular, two winding levels offset in a radial direction. For example, the device parts arranged in the inside of the hollow-cylindrical core of the coil body can be a reason for this offset. For example, the device part has a greater radial expanse in the upper region of the hollow cylindrical core than in the lower region. In order to save winding space toward the outside and, thus, keep the exterior dimensions of the magnet core optimally small toward the outside, it is then necessary to exploit, for example, the space becoming free toward the inside in the lower region with the winding level that is radially inwardly offset in this lower section. Such a fashioning of the winding space, however, is problematic, particularly in view of the standard, fully-automatic winding procedure.